The overall objective of this proposal is to develop a laser-based technology for micro-delivering powdered allergens for safer and faster epicutaneous immunotherapy, named EPIT. To date, allergen specific immunotherapy remains the only treatment for long-lasting clinical benefit to IgE-mediated allergies, but fewer than 5% o patients choose the treatment because of a risk of anaphylaxis and inconvenience. EPIT can potentially shorten the duration of the treatment and reduce anaphylactic risk because the epidermis is not only rich in antigen-presenting cells (APCs), but also a non-vascularized tissue. Unfortunately, epidermic delivery of allergen via intact skin faces numerous challenges as the skin is impermeable for macromolecules, whereas breaking skin barrier often triggers unwanted Th2 immune responses. We, along with others, have used ablative micro-fractional laser (AFL) to generate an array of self-renewable microchannels (MCs) in the skin for vaccine delivery and to elicit strong Th1 immune responses. These MCs offer unique advantages for EPIT as they not only serve as free paths for powdered allergens to enter the epidermis but also sustain the allergen in the epidermis constantly stimulating immune system that favors immune tolerance. Moreover, because the allergen is largely restricted inside the MCs anaphylaxis can be well prevented. We have created a simple way to fabricate a powder-based microarray patch (PMP), which gave rise to efficient epidermic delivery when applied onto laser-treated skin. We hypothesize that the laser-facilitated epidermic -delivery of powdered allergens/adjuvants can greatly augment efficacy of EPIT without incurring a risk of anaphylaxis. We will fabricate PMP with peanut protein extract (PPE), along with Th1 or immunosuppressant adjuvants. Epidermic delivery of PPE/adjuvants via laser-perforated skin will be optimized in naive and sensitized C3H/HeJ mice as well as in sensitized newborn pigs (Aim 1.1). Local innate immunity will be measured at the inoculation site and humoral immune responses against peanut allergens will be assayed in blood samples. We will also investigate Th1, Th2 and T regulatory (Treg) cells to corroborate Th1/Treg-predominant immunity against the allergen (Aim 1.2). Finally, we will seek in a murine peanut allergy model whether three doses of EPIT are superior to conventional 18 doses of subcutaneous immunotherapy in treatment of peanut allergy (Aim 2). IgE-mediated allergy occurs at an increasing rate in industrialized countries. This EPIT, if successful, would result in safer and faster treatments of peanut allergy and can be readily extended to other IgE-mediated allergies, which will have profound impact on public health systems.